One person took a bite and said, "Peanut butter! I love chocolate and peanut butter!"
Another sampled his slice and said, "But it isn't just peanut butter and chocolate. There's some other flavor in there."
I told them, "Bananas. It has bananas in it."
Yet a third person said, "Is this technically difficult to make? Because I really want the recipe."
The first two people chorused, "Us too. We want that recipe."
What makes this an unusual conversation is that this was at a birthday party and the speakers were all college sophomores. If you don't have any college aged kids, just think back to your own late teens to realize how unlikely this request for a recipe actually is, to say nothing of the entire conversation. Needless to say, this cake was popular.
Hannah's friend, Jenny, picked out this cake from Maida Heatter's Cakes. I had never seen a cake with such a combination of dominant flavors: chocolate, peanut butter, and bananas. We were all intensely curious to see what it was like.
It is hard to describe the taste, as you really can taste all those dominant ingredients, however, as reported above it was a huge success. Give it a try.
Heatter is well known for exhaustive instructions in her recipes. I revised a few of her technique notes for simplicity's sake ... and have adapted the recipe below to reflect those changes.
The icing contains a raw egg which would have worried me about salmonella if all I listened to were the sound bytes of major media. Here is a link which talks about food risks and raw eggs, which are much slighter than you would know from the way it is generally presented.
For the cake:
3 cups (12 ounces) all-purpose flour
1 tablespoon baking powder
2 teaspoons baking soda
1 teaspoon salt
Preheat oven to 350. Prepare 10 x 4" tube pan by buttering pan and then dusting all over with unsweetened cocoa powder. Tap excess cocoa out of pan and set aside.
Combine above dry ingredients and set aside.
8 ounces (2 sticks) unsalted butter
1 cup smooth peanut butter
1 tablespoon vanilla extract
1 pound (2-1/4 cups, packed) dark brown sugar
4 ounces semisweet chocolate, melted and cooled
1 cup (about 2) finely mashed, fully ripened bananas
1 cup strained unsweetened cocoa powder (preferably Dutch-process)
In the large bowl of an electric mixer, beat the butter until soft. Beat in the peanut butter and vanilla, then the sugar, scraping bowl as necessary with a rubber spatula. Next, mix in melted chocolate, then bananas, and then the eggs, one at a time, beating until incorporated after each addition. On lowest speed, add cocoa, still scraping bowl as necessary, and beat until smooth.
1-1/4 cups milk
On low speed, beating until smooth after each addition, gradually add about a third of sifted dry ingredients, the half of milk, then another third of dry ingredients, then remaining milk, and then remaining dry ingredients.
Turn mixture into prepared pan. Briskly rotate the pan a bit, first in one direction, then another, to smooth the top.
Bake for 1 hour, then cover the top loosely with foil to prevent overbrowning, and continue to bake for an additional 25 -30 minutes until a cake tester gently inserted into the cake comes out clean (total baking time 1 hour, 25-30 minutes). The top of the cake will crack during baking.
Cool in the pan on a rack for 20 minutes. Then cover with another rack, turn the pan and rack over, remove the pan and let the cake cool upside down on the rack.
For the icing:
16 ounces milk chocolate, broken up
2 ounces unsweetened chocolate, chopped coarsely
4 ounces (1 stick) unsalted butter, cut into 1/2" pieces
12 ounces (1-1/2 cups) smooth peanut butter
Melt both chocolates. Add butter a few pieces at a time, stirring with a wooden spoon until smooth.
In the large bowl of an electric mixer, beat the egg just to mix, then add the peanut butter and the chocolate mixture (which can be warm or cool) and beat until very smooth. As this mixture cools it will thicken; you might want to chill it quickly by putting it in the freezer or by placing the bowl in a larger bowl of ice and water. Or just let it stand a while. When it is thick enough to hold its shape beat it again for a moment.
This is a lot of icing and makes a thick layer. Spread it first on the sides and then on the top of the cake. With a long, narrow metal spatula, smooth the sides first and then the top.